relative risks for first level risk factor (vector of values corresponding
to the number of risk strata)

rr2

N

matrix of population size for each risk group
(rows = levels of rr1, cols = levels of rr2)

n

matrix of number tested (sample size) for each risk group
(rows = levels of rr1, cols = levels of rr2)

se

test unit sensitivity (scalar)

Value

list of 6 elements, a scalar of population-level sensitivity
a matrix of EPI values, a vector of corresponding Adjusted risks for
the first risk factor and a matrix of adjusted risks for the second risk factor,
a vector of population proportions for the first risk factor
and a matrix of population proportions for the second risk factor